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jkcmotox

A thousand 426 questions!

12 posts in this topic

I Just bought a barely used '01 426 from a local car dealer that took it in on trade. Stole it for $2500.00!!! Long story short, rode it twice (after full service) and it locked up the crank bearing. Took the bottom end to my favorite mechanic, cylinder to machinist for light honing and parts are on order, should have it up and running again by Saturday (which will give me time to tear apart my freshly seized '01 RM250...some guys have all the luck!)

So, while I have some down time with both bike's motors in the shop, I have some basic 426 questions. Any help will be greatly appreciated!

1. How many miles will a stock tank get you on fast open western desert terrain?

2. What is the best spark arrestor for "Blue Thunder", and does anyone make a replacement spark arrestor that just replaces the tip of the stock unit?

3. What are the "BK carb" and Blue wire" mods I keep hearing about?

4. Desert racers.....what gearing seems to work on this thing......I rode it with 14/48 and it felt alot slower than my 250 with only a few teeth smaller in the back. 15/46 maybe? And if so, does it pull something that high decently in the tight stuff or will I be replacing the clutch every race?

Can't figure out if it is actaully slower or just feels that way because I am not used to the 4 stroke power and and it's low rumble. Seemed like I was "shifting for 6th gear" alot in the fast stuff!

5. Should I be atleast mixing some race gas (I like Vp C-12) with 92 octane pump gas or is the 92 adequate for the thumper. 12.5:1 seems a little steep for straight pump gas to me!

6. I have been told that 3rd, 4th and 5th gear out of a WR will fit right into the tranny of the YZ to make it more desert racing friendly. Anybody done this mod?

7. What do I have to do to trick myself into thinking this thing is not heavy! Feels like my RM with a tank full of lead in it. Not bad on straights and great in the rocks, but man, in the technical sections I feel like I am on an XR650 or something. Guess it's hard to go back and forth between it and my 250 without always being reminded that it really ways 248 lbs no matter what Yamaha says it's dry weight is.

Again, any help would be highly appreciated, as this is my first thumper.

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2. What is the best spark arrestor for "Blue Thunder", and does anyone make a replacement spark arrestor that just replaces the tip of the stock unit?

---

Promoto Billet makes SA endcaps.

http://www.promotobillet.com

Also if you want a full silencer with SA.

FMF PowerCore IV -SA

WhiteBrothers E-series

GYT-R with SA insert ... to name a few. Do a search!

3. What are the "BK carb" and Blue wire" mods I keep hearing about?

look here.

http://motoman393.forreal.net/tech.html

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First off Welcome to TT,

Now before anyone else tells you I will, on the BK and Blue wire mods do a search or check out Motoman393's website(he has detailed instructions)

Weight wise you are gonna have a hard time switching back and forth between the two bikes. I went from a kx250 to my 426 and have never looked back. I wouldn't even know what to do with the new 450 as it is 13 pounds lighter or something like that. You can get alot of useful info on this sight just by searching. Don't be afraid to ask but at least give it a try searching in the search option to the top of the page. That's what I was instructed to do when I joined the site and it has helped alot. Good luck to you with the new motor, as for pump gas 93 is fine that is what 90% of us run with no problems. Also one more bit of advice, if and when you get your bike back running if it runs good and has little to no hesitation when you stab the throttle, then LEAVE IT ALONE! I wish I had of left mine alone because it took me months to get it dialed back in and it still isn't what it was when I got it. Good luck, Frank :)

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If your mechanic can tell you why it seized I would like to hear. I had a similar problem and it seems casting debris came off and went through the pick-up screen and pumped into the bottom bearing causing it to lock-up.Didn't do any major grenade type breakage inside but still cost a crank rebuild and all new seals and mains,plus decided to do new piston while I was in this far, just in case the rod put undue stress on wrist pin.Let me know if possible? Thanks!!

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Originally posted by jkcmotox:

So, while I have some down time with both bike's motors in the shop, I have some basic 426 questions. Any help will be greatly appreciated!

1. How many miles will a stock tank get you on fast open western desert terrain?

4. Desert racers.....what gearing seems to work on this thing......I rode it with 14/48 and it felt alot slower than my 250 with only a few teeth smaller in the back. 15/46 maybe? And if so, does it pull something that high decently in the tight stuff or will I be replacing the clutch every race?

Can't figure out if it is actaully slower or just feels that way because I am not used to the 4 stroke power and and it's low rumble. Seemed like I was "shifting for 6th gear" alot in the fast stuff!

5. Should I be atleast mixing some race gas (I like Vp C-12) with 92 octane pump gas or is the 92 adequate for the thumper. 12.5:1 seems a little steep for straight pump gas to me!

7. What do I have to do to trick myself into thinking this thing is not heavy! Feels like my RM with a tank full of lead in it. Not bad on straights and great in the rocks, but man, in the technical sections I feel like I am on an XR650 or something. Guess it's hard to go back and forth between it and my 250 without always being reminded that it really ways 248 lbs no matter what Yamaha says it's dry weight is.

Again, any help would be highly appreciated, as this is my first thumper.

1.

40-50

4.

I run 14/47. IMO you don’t need to be fanning the clutch for off-road events, just make sure you can operate it for the duration of the event to prevent brake-stalling it. If racing the YZF has a downside it is stalling it. I lost several places in my first few events on this bike until I learned to avoid stalling it (and jetted it properly to ensure easier starting, incl. BK mod, learned to bump start it quickly w/ the decomp, and bought a bar-mounted hot start and easy-pull Raptor clutch lever. Whew).

Back to the clutch issue, I only race four or five times a year, if I’m lucky, but I’ve never replaced any clutch plates. I probably have 150 hours on my ’00 and 200 on my ’01.

Back to the gearing. First gear is really tall, you won’t like a 47 tooth rear AT ALL if you are in the trees. You will barely tolerate a 51 tooth rear. However, in open terrain (sand washes, desert trails) I rarely bother with first gear even with 14/47 or even 15/49. I start (DE or otherwise) in second gear regardless.

5.

I wouldn’t bother with race gas, but a lot of guys swear by it. IMO getting the bike jetted properly for your climate and altitude is more important, I wonder how many guys are wasting money pouring VP-Whatever into a poorly jetted bike. If you want to run race gas take the time to jet it appropriately.

7.

Yes, it is heavy. Not much you can do about it really. Think of it as ballast that holds you in a straight line through the rock gardens. I’m a much better rider now, but I would never attack those things on my 250 like I do on my YZF.

Hope this helps you out some.

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You shouldn't need to cut any wires or fiddle with the accelerator pump on an '01 in my opinion, at least not if you are OK with stock jetting. Also for me pump fuel runs great, no problems at all.

Why did you have a lock up? That's definitely not normal, especially on a "barely used" bike. Be sure that you fix the cause of the problem!

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I put the 5th gear from the WR in my '01 YZF, and was very pleased with the results! That way I still have MX gearing for all of the tracks that I go to, yet when I jump on a fire road, LOOK OUT!!! Very nice, and not to expensive either! Maniac

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6. I have been told that 3rd, 4th and 5th gear out of a WR will fit right into the tranny of the YZ to make it more desert racing friendly. Anybody done this mod?

I put in a full 2001 wr transmission into my 2002, and it went in with out a problem.:banana: I race and ride desert.(ITS FAST!!!!!!):worthy::banana:

Good Luck!

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Holy :worthy: You dug up an old thread...7 years old.

oops....

i forgot i was searching for something....:banana::banana:

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oops....

i forgot i was searching for something....:banana::worthy:

hahah it happens

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